Fan bypass and shutoff check valve

ABSTRACT

A ram air fan and fan bypass shutoff check valve assembly includes a ram air fan configured to draw an airflow through a fan inlet, and a ram fan bypass duct positioned downstream of the ram air fan. The ram fan bypass duct includes a valve assembly configured to selectably direct the airflow through the ram air fan when the valve assembly is in an open position, and direct the airflow through a bypass duct thereby bypassing the ram air fan when the valve assembly is in a closed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/481,661 filed Apr. 07, 2017, the contents of which areincorporated by reference herein in their entirety.

BACKGROUND

Exemplary embodiments pertain to aircraft environmental control systems.More particularly, the present disclosure relates to a bypass control ofa ram air fan for an aircraft environmental control system.

Environmental control systems (ECS's) supply airflow to an interior ofan aircraft to condition, for example, a passenger cabin, crewcompartment and/or cargo compartment. In some ECS architectures a ramair fan is utilized to draw ram air into the ECS and across a ram airheat exchanger to condition a fluid flowing through the ram air heatexchanger. The ram air fan is driven by, for example an electric motoror a turbine. The typical air bearing ram air fan is not required tooperate during flight for performance reasons, but will uncontrollablywindmill during flight, if not driven by an electric motor or turbine.To control ram air fan rotation during flight and to keep the rotatingassembly supported by an air film, the ram air fan is typically poweredto operate at a specified minimum speed.

BRIEF DESCRIPTION

In one embodiment, a ram air fan and fan bypass shutoff check valveassembly includes a ram air fan configured to draw an airflow through afan inlet, and a ram fan bypass duct positioned downstream of the ramair fan. The ram fan bypass duct includes a valve assembly configured toselectably direct the airflow through the ram air fan when the valveassembly is in an open position, and direct the airflow through a bypassduct thereby bypassing the ram air fan when the valve assembly is in aclosed position.

Additionally or alternatively, in this or other embodiments the valveassembly includes a support having a plurality of support openingstherein in fluid communication with the bypass duct, an inner cagepositioned in the support having a plurality of cage openings therein,and a plurality of flappers rotatably secured to the inner cage. Theplurality of flappers are movable between the open position covering theplurality of support openings, and the closed position covering theplurality of cage openings.

Additionally or alternatively, in this or other embodiments theplurality of flappers are biased to the closed position.

Additionally or alternatively, in this or other embodiments each flapperof the plurality of flappers includes a spoiler extending from an outersurface of the flapper over which the airflow from the bypass duct isdirected to urge the flapper into the closed position.

Additionally or alternatively, in this or other embodiments the innercage includes a hub, an outer ring, and a plurality of spokes extendingfrom the hub to the outer ring. The plurality of cage openings areformed between adjacent spokes of the plurality of spokes.

Additionally or alternatively, in this or other embodiments theplurality of spokes are aerodynamically shaped.

Additionally or alternatively, in this or other embodiments theplurality of flaps rotate less than 45 degrees between the open positionand the closed position.

Additionally or alternatively, in this or other embodiments airflowthrough the bypass flow and airflow through the ram air fan exit the ramair fan assembly at a common passage exit.

In another embodiment, an environmental control system for an aircraftincludes a ram air heat exchanger and a ram air fan assembly operablyconnected to the ram air heat exchanger and configured to urge anairflow across the ram air heat exchanger. The ram air fan assemblyincludes a ram air fan and a ram fan bypass duct positioned downstreamof the ram air fan. The ram fan bypass duct includes a valve assemblyconfigured to selectably direct the airflow through the ram air fan whenthe valve assembly is in an open position, and direct the airflowthrough a bypass duct thereby bypassing the ram air fan when the valveassembly is in a closed position.

Additionally or alternatively, in this or other embodiments the valveassembly includes a support having a plurality of support openingstherein in fluid communication with the bypass duct, an inner cagelocated in the support having a plurality of cage openings therein, anda plurality of flappers rotatably secured to the inner cage. Theplurality of flappers movable between the open position covering theplurality of support openings, and the closed position covering theplurality of cage openings.

Additionally or alternatively, in this or other embodiments theplurality of flappers are biased to the closed position.

Additionally or alternatively, in this or other embodiments each flapperof the plurality of flappers includes a spoiler extending from an outersurface of the flapper over which the airflow from the bypass duct isdirected to urge the flapper into the closed position.

Additionally or alternatively, in this or other embodiments the innercage includes a hub, an outer ring, and a plurality of spokes extendingfrom the hub to the outer ring. The plurality of cage openings areformed between adjacent spokes of the plurality of spokes.

Additionally or alternatively, in this or other embodiments theplurality of spokes are aerodynamically shaped.

Additionally or alternatively, in this or other embodiments theplurality of flaps rotate less than 45 degrees between the open positionand the closed position.

In yet another embodiment, a check valve for a ram air fan assemblyincludes a support having a plurality of support openings therein influid communication with the bypass duct, an inner cage positioned inthe support having a plurality of cage openings therein, and a pluralityof flappers rotatably secured to the inner cage. The plurality offlappers are movable between the open position covering the plurality ofsupport openings, and the closed position covering the plurality of cageopenings.

Additionally or alternatively, in this or other embodiments theplurality of flappers are biased to the closed position.

Additionally or alternatively, in this or other embodiments each flapperof the plurality of flappers includes a spoiler extending from an outersurface of the flapper over which the airflow from a bypass duct isdirected to urge the flapper into the closed position.

Additionally or alternatively, in this or other embodiments the innercage includes a hub, an outer ring, and a plurality of spokes extendingfrom the hub to the outer ring, the plurality of cage openings formedbetween adjacent spokes of the plurality of spokes.

Additionally or alternatively, in this or other embodiments theplurality of spokes are aerodynamically shaped.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is schematic view of an embodiment of an environmental controlsystem for an aircraft;

FIG. 2 is a first cross-sectional view of an embodiment of a ram air fanand fan bypass/shutoff check valve assembly;

FIG. 3 is a second cross-sectional view of an embodiment of a ram airfan and fan bypass/shutoff check valve assembly;

FIG. 4 is a partial perspective view of an embodiment of a ram air fanand fan bypass/shutoff check valve assembly;

FIG. 5 is a partially exploded view of an embodiment of a ram air fanand fan bypass/shutoff check valve assembly;

FIG. 6 is another partial perspective view of an embodiment of a ram airfan and fan bypass/shutoff check valve assembly;

FIG. 7 another cross-sectional view of an embodiment of a ram air fanand fan bypass/shutoff check valve assembly; and

FIG. 8 is yet another cross-sectional view of an embodiment of a ram airfan and fan bypass/shutoff check valve assembly.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

The term “about” is intended to include the degree of error associatedwith measurement of the particular quantity based upon the equipmentavailable at the time of filing the application. For example, “about”can include a range of ±8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,element components, and/or groups thereof.

Referring to FIG. 1, a schematic illustration of an environmentalcontrol system (ECS) 10 for an aircraft is shown. The ECS 10 includes aram air heat exchanger 12 and a ram air fan assembly 14 to draw a ramairflow 16 across the ram air heat exchanger 12 to condition a fluidflowing through the ram air heat exchanger 12. The ram airflow 16 thenflows through ram air passage 18, through the ram air fan assembly 14and out of a passage exit 20.

Referring to FIG. 2, the ram air fan assembly 14 includes a fan housing22, in which a ram air fan 24 is located, and is rotatable about acentral axis 26. The fan housing 22 is in flow communication with theram air duct 28 downstream of the ram air heat exchanger 12. In theembodiment illustrated, the ram air fan 24 is driven by a tip turbine 30located in the fan housing 22 radially outboard of the ram air fan 24. Aram fan bypass duct 32 is located downstream of the fan housing 22 andincludes a fan bypass/shutoff check valve consisting of an outer housing34 and an inner cage 36 located therein. The outer housing 34 includes asupport 38 and a plurality of flappers 40 rotationally movable betweenan opened position shown in FIG. 2 in which airflow 42 proceeds throughthe ram air fan 24 and through the passage exit 20, and a bypassposition, shown in FIG. 3, in which airflow 42 bypasses the ram air fan24 and proceeds through a bypass passage 44 in the ram fan bypass duct32 to the passage exit 20.

Referring now to FIG. 4, the support 38 includes a plurality of supportopenings 46, the quantity of support openings 46 corresponding to thequantity of flappers 40 in the plurality of flappers 40. In someembodiments, there are 8 support openings 46 and 8 flappers 40, but itis to be appreciated that other quantities may be used. When in theopened position, as shown in FIG. 2 and FIG. 4, each flapper 40 engagesto the support 38, closing a respective support opening 46. In someembodiments, the support openings 46 are recessed into the support 38such that when the flapper 40 engages the support 38 at the supportopening 46 an inner flapper surface is flush with an inner supportsurface, such that there is a positive seal and a smooth flowpath alongthe inner support surface, reducing pressure drop along the support 38.

Further, the inner cage 36 includes a plurality of inner cage openings48, shown best in the exploded view of FIG. 5. In the view of FIG. 2 andFIG. 4, with the flappers 40 in the opened position, the airflow 42 isdirected from the ram air fan 24, through the plurality of inner cageopenings 48, and through the passage exit 20. When the ram air fan 24 isoperating, positive air pressure across the ram air fan 24 forces theflappers 40 into the opened position.

FIG. 6 further illustrates the plurality of flappers 40 in a closedposition. When in the closed position, the flappers 40 engage the innercage 36 covering the plurality of inner cage openings 48. Referring toFIG. 3, with the inner cage openings 48 covered, the airflow 42 isdiverted through the bypass passage 44 and to the passage exit 20,bypassing the ram air fan 24.

The flappers 40 are each connected to the support 38 via, for example, ahinge connection 50 at a pivot axis 52. To move between the openposition, illustrated in FIG. 2 and the closed position illustrated inFIG. 6, the flapper 40 is rotated about the pivot axis 52. In someembodiments, an angle of rotation of the flapper 40 between the openposition and closed position is less than 45 degrees. In otherembodiments, the angle of rotation is 40 degrees.

In some embodiments, the flappers 40 are biased toward the closedposition by, for example, a spring or other biasing device (not shown).When the ram air fan 24 is commanded to stop, the flappers 40 move tothe closed position due to the lack of positive pressure across the ramair fan 24, and because of the influence of the biasing device. Further,in some embodiments, as shown in FIG. 7, the flapper 40 includes anaerodynamic spoiler 56 extending from an outer surface 58 of the flapper40, such that the airflow 42 flowing though the bypass passage 44 flowsover the spoiler 56, exerting aerodynamic forces on the spoiler 56 andurging the flappers 40 into engagement with the inner cage 36 coveringthe cage openings 48. In some embodiments, the spoiler 56 extendssubstantially perpendicularly to a direction of the airflow 42 exitingthe bypass passage 44.

Referring again to FIG. 5 and FIG. 7, the inner cage 36 includes a hub60 located at the central axis 26 and an outer ring 62 coaxial with thehub 60 and defining a radial outwardmost extent of the inner cage 36. Aplurality of spokes 64 extend from the hub 60 to the outer ring 62defining the cage openings 48 between adjacent spokes 62. As shown inFIG. 8, the spokes 64 each have a cross-sectional shape configured toreduce pressure drop through the cage openings 48. As shown the spokes64 may have a tapered V cross-sectional shape, or alternatively anothercross-sectional shape, such as an airfoil shape.

The ram fan bypass duct 32 including the inner cage 36 and flappers 40movable between the inner cage 36 and the support 38, allows airflow 42to bypass the ram air fan 24 in-flight thus preventing windmilling ofthe ram air fan 24 and preventing the need to power the ram air fan 24during flight to provide airflow to an air bearing of the ram air fan24.

While the present disclosure has been described with reference to anexemplary embodiment or embodiments, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements thereof without departing from the scope ofthe present disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of the presentdisclosure without departing from the essential scope thereof.Therefore, it is intended that the present disclosure not be limited tothe particular embodiment disclosed as the best mode contemplated forcarrying out this present disclosure, but that the present disclosurewill include all embodiments falling within the scope of the claims.

What is claimed is:
 1. A check valve for a ram air fan assembly,comprising: a support having a plurality of support openings therein influid communication with the bypass duct; an inner cage disposed in thesupport having a plurality of cage openings therein; and a plurality offlappers rotatably secured to the inner cage, the plurality of flappersmovable between the open position covering the plurality of supportopenings, and the closed position covering the plurality of cageopenings.
 2. The check valve of claim 1, wherein the plurality offlappers are biased to the closed position.
 3. The check valve of claim1, wherein each flapper of the plurality of flappers includes a spoilerextending from an outer surface of the flapper over which the airflowfrom a bypass duct is directed to urge the flapper into the closedposition.
 4. The check valve of claim 1, wherein the inner cageincludes: a hub; an outer ring; and a plurality of spokes extending fromthe hub to the outer ring, the plurality of cage openings formed betweenadjacent spokes of the plurality of spokes.
 5. The check valve of claim4, wherein the plurality of spokes are aerodynamically shaped.